[PATCH 20/34] drm/amd/display: Update and revert FRL LT Timeout behaviour

From: Relja Vojvodic <[email protected]>

[Why & How]
- Revert logic to fallback to polling if LT no timeout is set
- Update LT timeout to 300ms for appropriate link rates

Reviewed-by: Nicholas Kazlauskas <[email protected]>
Signed-off-by: Relja Vojvodic <[email protected]>
Signed-off-by: Tom Chung <[email protected]>
---
 .../display/dc/link/protocols/link_hdmi_frl.c | 32 +++++++++----------
 1 file changed, 15 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_hdmi_frl.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_hdmi_frl.c
index 714168e1ece6..7f930097da18 100644
--- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_hdmi_frl.c
+++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_hdmi_frl.c
@@ -528,10 +528,10 @@ static enum link_result hdmi_frl_perform_link_training(struct ddc_service *ddc_s
 
 		FRL_INFO("FRL LINK TRAINING:  Poll for FLT_UPDATE.\n");
 		/*LTS:3: Start Link Training*/
-		/*Start FLT Timer = 200 ms*/
+		/*Start FLT Timer = 200 ms, or 300ms if link rate >= 16Gbps*/
 		num_polls = 0;
-		if (flt_no_timeout)
-			max_polls = 500;
+		if (link_settings->frl_link_rate >= HDMI_FRL_LINK_RATE_16GBPS)
+			max_polls = 155;
 
 		while (num_polls < max_polls) {
 			flt_poll_cur_time = dm_get_timestamp(ddc_service->ctx);
@@ -572,7 +572,7 @@ static enum link_result hdmi_frl_perform_link_training(struct ddc_service *ddc_s
 				FRL_INFO("FRL LINK TRAINING:  TxFFE = %d.\n", current_FFE);
 				override_FFE = false;
 			}
-			if (scdc_update.fields.FLT_UPDATE) {
+			if (scdc_update.fields.FLT_UPDATE || flt_no_timeout) {
 				offset = HDMI_SCDC_LTP_REQ;
 				link_query_ddc_data(ddc_service, slave_address,
 								&offset, sizeof(offset), ltp_req.byte,
@@ -680,21 +680,19 @@ static enum link_result hdmi_frl_perform_link_training(struct ddc_service *ddc_s
 				/* Workaround for DEDCN3AG-111
 				 * HDMI-FRL Incorrect Serialization Order for LTP4
 				 */
+				if (flt_no_timeout) {
+					return LINK_RESULT_SUCCESS;
+				}
 			}
-
-		}
-		if (flt_no_timeout) {
-			return LINK_RESULT_SUCCESS;
-		} else {
-			FRL_INFO("FRL LINK TRAINING:  FAILED - Timeout waiting for FLT_UPDATE to be set by sink.\n");
-			write_buffer[0] = HDMI_SCDC_CONFIG_1;
-			/*FRL_RATE*/
-			write_buffer[1] = HDMI_FRL_LINK_RATE_DISABLE | (0 << 4);
-			link_query_ddc_data(ddc_service, slave_address,
-					write_buffer, sizeof(write_buffer), NULL, 0);
-			hdmi_frl_LTS_clear_Link_Setting(ddc_service);
-			result = LINK_RESULT_TIMEOUT;
 		}
+		FRL_INFO("FRL LINK TRAINING:  FAILED - Timeout waiting for FLT_UPDATE to be set by sink.\n");
+		write_buffer[0] = HDMI_SCDC_CONFIG_1;
+		/*FRL_RATE*/
+		write_buffer[1] = HDMI_FRL_LINK_RATE_DISABLE | (0 << 4);
+		link_query_ddc_data(ddc_service, slave_address,
+				write_buffer, sizeof(write_buffer), NULL, 0);
+		hdmi_frl_LTS_clear_Link_Setting(ddc_service);
+		result = LINK_RESULT_TIMEOUT;
 	} else {
 		FRL_INFO("FRL LINK TRAINING:  FAILED - FLT_READY not set by sink.\n");
 		result = LINK_RESULT_TIMEOUT;
-- 
2.43.0